This invention relates to an automatic developing machine for developing photosensitive materials such as exposed films or printed photographic paper.
An automatic developing machine for developing photosensitive materials such as films and photographic paper have treating tanks filled with different treating solutions such as developing, bleaching, fixing and stabilizing solutions. Photosensitive materials are fed through these solutions in the treating tanks for development, bleaching and other treatments.
As shown in FIG. 5, a conventional means for storing such a treating solution is typically made up of a treating tank 21 and a sub-tank 22 communicating with the treating tank 21 through a return passage 23 and a supply passage 24. To maintain the activity of the treating solution, it is circulated between the treating tank 21 and the sub-tank 22 by means of a circulation pump 25 provided in the supply passage 24.
The concentration of a treating solution changes with the amount of photosensitive materials treated. If the concentration is too low, it is impossible to treat photosensitive materials properly. Thus, it is necessary to adjust the concentration according to the change.
One conventional method of adjusting the concentration of the solution in the treating tank is to store a solution having a predetermined concentration in the sub-tank. But it takes a substantial time to prepare such a solution having a predetermined concentration. Such a solution has to be stored in an extra tank provided in the developing machine. This increases the size of the developing machine.
To solve these problems, International Patent Publication WO 92/20013 proposes to supply a solid treating agent containing components necessary for the treatment of photosensitive materials into the sub-tank and dissolve it in the solution to adjust its concentration.
This type of automatic developing machine has a supply unit 26 for supplying a solid treating agent. Since it is mounted over the sub-tank 22 as shown in FIG. 5, the developing machine is rather large in size. Also, gas produced from the treating solution in the sub-tank 22 tends to rise and invade the supply unit 26. On contact with such gas, a plurality of small pieces of treating agent tend to stick together, forming larger lumps. This makes it difficult to supply a predetermined amount of treating agent into the sub-tank.
A first object of this invention is to provide a small-sized, compact automatic developing machine.
A second object is to provide an automatic developing machine which can prevent tablets used for the adjustment of solution concentration from sticking together, so that a predetermined number of tablets can be supplied reliably.